Air conditioning system



Feb. 24,1942. w. l.. MGGRATH AIR CONDITIONING SYSTEM Filed July' 1e, 1957 2 sneetsneet 1 SPACE HUMIDITY vFeb. 24, 1942. w, L, MQGRATH f 2,274,152

AIR CONDITIONING SYSTEM Filed July 1e, 1937 2 sheets-sheet 2 lap/Ica HuMllorrY Amit/fw l Patented Feb. 24, 1942 AIR CONDITIONING SYSTEM William L. McGrath, St. Paul, Minn., assignor to` Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application July 16, 1937, serialfNo. 154,026

28 Claims.

My invention relates toair conditioning systems and is more particularly concerned with automatic controls therefor.

The primary object of vmy invention is to provide a novel automatic air conditioning system which is especially adapted to utilize an internal combustion engine driven refrigeration system for economically maintaining the temperature and humidity conditions vof the interior of buildings orother structures Within desired ranges of values.

One object of my invention is to provide an air conditioning system which employs an internal combustion engine as a driving means, such system being arranged for recovering the Waste heat given off by such engine to. provide reheat, and for also providing a source of heat for other purposes such, for instance, as for providing a supply of domestic hot water.

More specically, it is an object of my invention to provide a closed system of this type with a simple and elcient arrangement for cooling the.l

condenser of the refrigeration system and for recovering the heat dissipated by the internal combustion engine, thereby rendering the heat re` moved from the conditioned space and the waste heat from the engine available for providing a supply of domestic hot water and for providing reheat when necessary. `With a system of this l type the heat rendered available is o ten in excess of that needed for reheat or for heating domestic water, and consequently it is often neces,

the conditioned space within predetermined limits. In accordance with this phase of my invention, I provide for controlling the compressor output in a manner to increase said output upon increase in space temperature thereby decreasing the cooling coil temperature upon such increase in space temperature. For controlling the space relative humidity, I provide -damper means con- `trolling the air ilow across the .cooling coil, and

further provide a reheater. the damper means and the reheater being controlled -by a humidity` controller in a manner to rst decrease the flow of air across the cooling coil when the humidity becomes excessive, and then to place 'the reheater in operation. By this arrangement the cooling dehumidication ratio of the cooling coil is varied to maintain both proper temperature conditions and proper humidity conditions, reheat being supplied whenever necessary and only when necessary for achieving this result.

Another object of my invention is the'provision of an air conditioning system of the type employing a compressionl refrigeration system, with a modulating comp'ressor' output `controller for maintaining a constant but adjustable refrigeration coil temperature, such controller being supplemented by a second controller responsive to the refrigeration load for varying the refrigeration coil temperature in a manner to maintain desired psychrometric conditions within the conditioned space, the control system being also adapted to automatically start the compressor when the pair of`controllers demand a compressor output above a predetermined minimum value, said controllers acting also to place the compressor out of operation when the output demand is below such minimum value.I

Further objects of my invention are the provision of an arrangement for limiting the action of the reheater to prevent overheating of the air by the reheater,` and the provision of an arrangement for placing the internal combustion engine out of operation when the fan is stopped.

While my invention is'more particularly concerned with air conditioning systems utilizing gas engines, certain novel features are of broader application.

Other objects of my invention will appear from modifications and'additions to the system of Figi ure 1l.

In thedrawingareference character I indicates an air conditioning chamber, thischamber having a returnair inlet 2 which is connected by suitable duct means to the space to be conditioned 3. Said conditioning chamber is also provided with a fresh air inlet which is connected to .the fresh air duct 4, suitable damper means (not shown) being provided for controlling the ad- 'space 3. The fan 5 may be driven by any suitable means and is herein shown as being driven by an electric motor 1 receiving its power from line wires 8 and 9. Within the conditioning chamber I is located a cooling coil I0, a partition I I being disposed thereabove for providing a bypass passage for the air aroundsaid coil. The flow of air over the coil and through the by-pass passage is controlled by means of a set of face dampers I2 and a set of by-pass dampers I3, these dampers being actuated in unison by means of an operating rod I4 which is secured to the operating arm I5 of an electric proportioning motor I6. The proportioning motor I6 is pref- ,erably of the type shown and described. in Patent N6. 1,989,972 issued on May 22, 1935, to Lewis L. Cunningham. This type of proportioning mor tor `isfauapted to be controlled by means of a potentiometer controller, and in accordance with my invention is controlled by means of the potentiometer type of space relative humidity controller generally indicated at I8. It will be understood that upon upward movement of the operating arm I5 of the proportioning motor I6 the face dampers I2 will be moved towards closed position and the by-pass dampers I3 will simultaneously be moved towards open position, thereby decreasing the now of air across the cooling `coil I and increasing the ow of air through the by-pass, and upon downward movement of the operating arm I the opposite action will take place. Also located within the conditioning chamber I is a reheater I9, this reheater being provided for heating the cooled air under certain conditions.

The cooling coil I0 is herein shown as being of the direct expansion type. For supplying liquid refrigerant to said cooling coil and for withdrawing the evaporated refrigerant therefrom, a compression type of condensing unit is provided, this condensing unit comprising a compressor 20 and a 'condenser 2|. The discharge `of the compressor is' connected by a discharge line 22 to the refrigerant inletl of the condenser 2-I. The refrigerant outlet 'of the condenser 2l is connected to a conduit 23, this conduit conveying the liquid refrigerant .to the expansion v'alve 24 which is connected to the inlet of the cooling coil Ill. rZafhis expansion valve 24 may be of any such for instance, as a gas engine, a Diesel engine, or a gasoline engine, and is herein shown as being provided with an inlet manifold 21 havv.ing connected thereto a fuel supply pipe 28, a

. the conditioned space.

throttle valve 29 being located in said fuel supply pipe for controlling the supply of fuel and hence the output of the engine. The internal `combustion engine 26 is also provided with an exhaust manifold 30, a generator 3I, and a starting motor 32. To the vily-wheel 33 of said engine is connected a drive shaft 34, this drive shaft having mounted thereon pulleys 35 and 36. The y pulley 35 cooperates with suitable belts to drive the compressor 28, while the pulley 36 provides for-driving a heat exchange fluid circulating pump 31.

In accordance with my invention, the operation of the internal combustion engine 26 is controlled in a manner to maintain a constant .but adjustable cooling coil temperature, the cooling coil temperature maintained being varied in accordance with the temperature of the air within This control is achieved by the use of a proportioning motor generally indicated at 40, a suction pressure controller 4I, and a return air temperaturel controller42.

Referring now to the proportioning motor 40, thismotor comprises an operating shaft 43 for rotating the operating arm 44, which is connectedby suitable linkage to the throttle valve 29. Whilev I have shown the proportioning motor as positioning the throttle valve 29 directly, it will be understood that if desired the proportioning'motor 40 may be arranged to adjust a speed regulator or governor for the engine which in turn operates said throttle valve. The operating shaft 43l ,l is driven through a suitable gear train 45 by a reversible velectric motor means comprising apair of armatures 46 and 41 cooperating with respective field coils 48 and 49. The armature 46 and the field coil 48 comprise an induction motor for driving the operating shaft 43 in one direction, and the armature 41 and the field coil 49 comprise an induction motor for 41 driving said operating shaft in the opposite di desired type and is shown herein as being of the thermostatic type controlled in yaccordance with the outlet temperature offthe cooling coil. It will be understood that a suitable receiver (not shown) may be interposed between the condenser and the expansion valve in accordance with established practice.v The outlet of the cooling coil III is connected to an outlet conduit or suction line 25 to the suctionside of the compressor 20. The operation of compression refrigeration systems of this type is well known in the art and therefore no detailed description of the operation of this system is necessary. It may be stated,

however, that operation of the compressor 2I causes chilling vof the' cooling coil I0 and the temper'ature of the cooling coil I0 will vary in ac-i cordance with the speed of the compressor and in accordance with the quantity and temperature of the air passed/over said cooling coil.

The compressor 20 is driven by means of an internal combustion -engine 26. Ihis internal y combustion engine may be of any suitable type,

rection. The energization of the i-leld coils 48 and 49 is controlled by means of a suitable balancing relay 50; and by means of suitable limit switches 5I and 52. The limit switches 5I and 52 may .be of any desired construction, and are shown herein as comprising normally engaged flexible contact blades. which are adapted to be separated by means of an actuating member 53 which is mounted upon the operating shaft 43. It will be understood that when the operating shaft 43 rotates to either limit of rotation the operating member 53 will cause opening of the appropriate limit switch for deenergizing the operating motor to prevent injury to the apparatus. Referring now to the balancing relay58, this is shown as comprising a pair of serially connected relay coils 54 and 55. These relay coils are adapted to control through a suitable armature (not shown) a switch arm 56 which cooper- 'ates with a pair of contacts 51 and 58. When gage the contact 51. Conversely, when the relay coil 55 is energized more highly than coil 54,

l th'e switch arm 56 will be brought intoV engagement with contact 58.- Thej relative energization oi the relay coils 54 and 55 is controlled by means .of the potentiometer type of controllersI 4| and v`42 and also by means Vof a balancing potentiometer 68, this potentiometer comprising a balancing arm 6| which is adapted to be rotated by rotation of the operating shaft 43, this balancing arm contacting with a balancing resistance 62. Upon clockwise rotation of the shaft 43, the balancing arm 6| will be' shifted tothe right across the balancing resistance 62, and upon opposite rotation of the shaft 43 movement of the balancing arm in the opposite direction will take place Referring-now to the suction pressure controller 4|, this controller comprises a bellows 64, this bellows being connected by a pipe 65 to the suction line 25 which leads from the outlet of the cooling coil I8 to the compressor 28,.l The bellows 64 is arranged to actuatea pivoted actuating arm 66, this arm having secured thereto a control arm 61 and a corrector arm 68. The control arm61 is arranged to engage a control resistance 68 for forming a control potentiometer,-

andthe correctorarm 68 is arranged to engage a corrector resistance 18. For urging the actuating arm 66 against the bellows, a tension spring 1I is provided, this spring being connected to the end of the actuating arm and toa suitable fixed element. It will be apparent that as the suction pressure increases, the bellows 64 will expand, thus tilting actuating arm 66 upwardly against the action .of the spring 1|, thereby causing counter-clockwise rotation of the arms 61 and 68 across their respective resistancs. Upon a decrease in suction pressure, the opposite action will take place, namely, the bellows 64 will contract under the a'ction of the spring 1|, thereby causing rotation of the arms 61 and 68 in a clockwise direction.

Thereturn air temperature controller 42 cornprises abellows 12, this bellows being connected by a capillary tube 13 to a control bulb 14 located in the return air passage. The bellows, tube, and

bulb contain a suitable volatile fluid wherefore the vapor pressure within the bellows varies in accordance with changes in temperature at the control bulb 14. 'Ihe bellows 12 actuates a pivoted bell-crank member having an actuating arm and a control arm 16, said controlarm cooperating with acontrol resistance 11 for forming a control potentiometer. A spring 18 is attached to the end of the actuating arm 15 for urging said arm against the bellows 12. Upon an increase in return air temperature, the vapor pressure of the volatile fill will increase, thereby causing expansion of the bellows 12 against the action of the spring 18, this causing upward .movement of the actuating arm 15 and movement of the control arm 16 to the right across the resistance. 11. .'Upon a fall in return air temperature, the vapor pressure of the volatile fill will decrease, this causing contraction of the bellows 12 by the action of the spring 18, which results in the control arm 16 being shifted towards the left across the resistance 11.

Reference character 88 indicates a step-down transformer having a high voltage primary 8| and a low voltage secondary 82. One side of -tbe secondary 82 is connected by `wire 83 to the leftA l 3 of wires 88, 85, 88 and 81, while the right-hand end of resistance 11 and the left-hand end of resistance 61 are connected to the upper terminal of said transformer secondary by means of wires 84, 88, 88 and 88. The lower end of the transformer secondary is also connected to the left end of balancing resistance 62 by Wires 83 and 8|, while the upper end of said secondary is connected to the right-hand end of the balancing resistance by wires 84 and 82. By the 'wiring arrangement just described, it will be apparent that the resistances 62, 68 and 11 are connected `in parallel across the transformer secondary along with the relay coils 54 and 55 which are connected across said secondary in series. yA ow of current will therefore take place through each of the resistances and through the relay coils 54 Vand 55. To the junction of the relay coils 54 and 55 is connected a wire 83, this wire being connected t'o the corrector resistance 18 of the controller, 4| and to the control arm 16 df the temperature controller 42 through a rheo` stat V84. The wire 83 is also connected to a wire 85, which in turn is connected to the balancing arm 6I of the balancing potentiometer, a rheostat 86 being interposed in said wire. By the wiring just described the balancing arm 6 I, the control arm 61, and the control Iarm 16 are connected to the junction of the relay coils 54 and 55. This has the effect of causing each of the control arms and the balancing arm to divide its respective resistance into` a rst portion,

which is parallel with the relay coil 54, and into a second portion which is in parallel with the relay coil 55.` Therefore, movement oi' either of they controlarms or the, balancing arm' across its resistance will change the value of resistance in parallel with the relay coils 54 and 55, thereby at which time the switch arm 56 will be disengaged. from both contact 51 and contact 58.

' Assuming now that the return air temperature remains constant, if thesuction pressure should increase, the control arm 61 of the controller 4| will be shifted in a counter-clockwise direction, this decreasing the portion of resistance 68 which is'in parallel with relay coil 55 and increasing the porticnof said resistance which is in Rarallel with relay coil 54, this causing an increase in current flow in coil 54 and a decrease in current flow in coil 55. This will result in switch arm 56 engaging the contact 51y and energizing the motor field 48 bv a circuit as follows: transformer secondary 82, wire 84, wire 82, wire 88, switch arm 56, contact 51, wire 88, limit switch 52. wire |88, motor field 48, and wire |8| to the motor field 48 will cause the operating shaft 48 hand end of the relay coil 54. and the other side of said secondary is connected by wire 84 to the right-hand end of relay coil 55. The relay coils 54 and 55 are therefore connected in series acre"-s the terminals of the transformer secondary 82. Theleft-hand end of resistance 11 and the righthand end of resistance 68 are connected to the lower end of transformer secondary 82 by means to be driven in a counter-clockwise direction, this causing opening of the throttle valve 28 to increase the speed of the engine. Simultaneously, with the opening movement of the throttle valve 28, the balancing arm 6| will be shifted to the left across the balancing resistance 62, this decreasing the portion of said resistance which is in `parallel with the relay coil 54 and increasing the portion of said resistance which is in parallel with the relay coil 55, thus tending to balance out the initial unbalancing effect of the controller 4|. When the rotation of the shaft 43 results in such movementl of the balancing arm 6l that the initial `unbalancing effect of the controller 4| is balanced out, the switch arm 56 will disengage the contact 51 thereby deenergizing mo'tor field 49, thus stopping the throttle valve 29 at this new position.

Upon a decrease in suction pressure the control arm 61 of the controller 4I will be shifted to the right across the control resistance .69, this decreasing the portion of said resistance which is in parallel with relay coil 54 and increasing the portion of said resistance which is in parallel with the relay coil 55. This will result in increasing'the current ow in relay coil 55 and decreasing the current ow in relay coil 54, `this causing switch arm 56 to engage the contact 5,8. and in a' manner which will be apparent, will energize the motor field 48 for rotating the operating shaft 43 in a direction to close the throttle valve 29. As the throttle valve 29 is closing, the balancing arm 6i t be shifted to the right across the balancing resistance 62, thereby causing anincrease in current fiow in the relay coil 54 and a decrease in current flow in relay coil 55, this tending to balance out the initial unbalancing effect of the controller 4I. When the movement of the throttle valve 29 is such that the balancing potentiometer rebalances the relay 50, the switch arm 56 will `disengage the contact 58, thereby causing deenergization of the motor eld 48, thus allowing the throttle valve 29 to remain in its new position. It will be apparent that for a given movement of the control arm 61 upon its control resistance, a corresponding movement of the balancing arxn 6I on the balancing resistance 62 will be required forrebalancing the relay. Therefore, the movement of the throttle valve will be proportionate to the movement of the control arm 61 on its control resistance. The control arrangement just described, therefore, will act to position the throttle valve in accordance with changes in suction pressure, the throttle valve being opened for increasing the engine speed upon an increase in suction pressure, and being closed for decreasing the engine speed upon fall in suction pressure.

Assuming now that the suction pressure remains constant, if the return air temperature should increase, the control arm 16 of the controller 42 will be shifted to the right across the resistance 11, this decreasing the portion of said resistance which is in parallel with relay coil 55 and increasing the portion of said resistance which is in parallel with relay coil 54. This will cause the relay coil 54 to be more highly energized than coil 55 and will result in switch arm 56 engaging the contact 51for driving the operating shaft 43 and the throttle valve 29 towards open position thus increasing the engine speed. In a manner which should now be apparent, when the movement of the throttle valve is such that the balancing potentiometer rebalances this unbalancing effect of the controller 42, the throttle valve 29 will be stopped in its new position. Upon a decrease in return air temperature, it will be apparent that the opposite action will take place, namely, that the throttle valve will be caused to be shifted towards closed position an amount proportionate to Y the decrease in temperature.

The purpose of the return air temperature controller 42 is to adjust the value of suction pressure which will be maintained by the suction pressure controller 4I in accordance with changes in return air temperature. As the suction pressure controller 4 I therefore, is to maintain varying values of suction pressure, it is necessary to make the operating range of said controller less .than its total range. In other words, it is necessary to arrange said controller so that a movement of the control arm 61 through but part of its range will cause the throttle valve to be shifted from full open to full closed position and vice versa. For this purpose, the rheostat 96 is inserted between the balancing arm 6| and the junction of the relay coils 54 and 55. This rheo stat has the function of decreasing the current flow through the balancing arm 6| and therefore decreases the sensitivity or rebalancing effect of the balancing potentiometer. By the use of this'rheostat, asmall movement of the control arm 61 on the resistance 69 may be made to cause such an unbalancing of the relay coils that a relatively large movement of the balancing arm is required for rebalancing. By properly adjusting the rheostat 96, a predetermined change in value of suction pressure may cause a movement of' the throttle valve 29 from one extreme to the other. 'I'he rheostat 96 therefore makes the operating range of the controller 4I less than its total range of operation.

As above stated, the controller 42 acts. to adjust the value of suction pressure maintained by the controller 4I. This action is accomplished 'as follows. Assuming a constant suction pressure and a rise in return air temperature, the controller 42 will be shifted to cause opening of the throttle valve 29 an amount determined by the degree of temperature rise. This opening movement of the throttle valve 29 will increase the fuel supply tothe engine, thereby increasing its speed. The resulting increase of the compressor speed will result in the suction pressure beginning to fall. In response to this decrease in suction pressure, the controller 4I will begin shifting the throttle valve 29 towards closed position thus decreasing the speed of the engine, and when the suction pressure falls to such an extent that the resulting decrease in operation of the compressor stops further fall in suction pressure, the suction pressure will be maintained constant at this point. An increase in space temperature, thereforey will have the effect of causing the controller 4I to maintain a lower suction pressure. A decrease in space temperature will have the opposite effect, that is, the controller 42 'will act tor close the ginning to rise. In response to this rise in suction pressure, the controller 4I will begin moving the throttle valve towards openposition to increase the speed of the compressor, and when the suction pressure has increased to such an extent that the resulting increase in operation of the compressor prevents further suction pressure increase, the suction pressure will remain constant at this point. Upon falling space temperature, therefore, the suction pressure'controller will be adjusted to maintain a higher value of suction pressure. It will be noted that the rheostat 94 is interposed between the control arm 16 of controller 42 and the junction of .the relay coils 54 and 55. 'I'he purpose of this rheostat is to provide an adjustment for varying the effect of changes in temperature upon the suction presby properly adjusting this rheostat, any desired 6' change in lsuction. pressure for a given change in space temperature may be obtained. The purpose of the corrector arm 69 and the corrector resistance on the controller 42 is for compensating or correcting the operation of the'conl0 troller 4| when the value of suction pressure maintained is near either limit of the range of said contro1ler.`

From the foregoing description, .it should be seen that'the controllers 4| and 42 conjointly 15 control the throttlevalve 29 to vary the speed of the compressor hence the r"coil temperature in a manner to meet the prevailing refrigeration load. In accordance Vwith my invention, I also provide an arrangement whereby these control- 1ers act to cause starting of the internal combustion engine whenever the refrigeration load is suilcient to justify operation of said engine and tocause stopping of said engine when the refrigeration load is so4 light that ineilicient operation 25' of the engine would result. For obtaining thisl result, an auxiliary .switch generally indicated as |02 is mounted to be actuated by the operating shaft 43 of the proportioning motor 40. Switch |02' comprises .a bell-crank member having an 30 o actuating arm |03 and a switch carrying- Varm car' ying a mercury switch |04. Mounted, upon the operating shaft 43 is a switch operating 'nember |05, this operating member being arranged to engage `the actuating arm |03 and 35 rotate the bell-crank lever so that mercury switch |04 is tilted to open position when the throttle valve 29 is moved to ay predetermined closed position. When the throttle valve is opened to a predetermined position, howeverthe, operating member |05 will be rotated so as to permit a spring |06 to tilt the mercury switch |04 to closed position. The mercury 'switch |04 is connected to controla suitable automatic starting and stopping control mechanism for the engine 29. For purposes of illustration, I have shown this control mechanism as being of the typeillustrated in the Loehr Patent'No. 1,773,913 issued August 26, 1930.- It will be noted that one terminal of the mercury switch |04 is connected to 50 a storagey battery |01 by a wire |08, the other terminal of the storage battery being grounded. The other terminal of the mercury switch |04 is connected by wires |09 and |09a toan ignition coil IIO, and by the wire |09 to a starting relay 55 By this arrangement,v whenf the mercury switch |04 is tilted to vclosed position due to the .throttle valve 29 being opened to a predetermined position, the ignition circuit for the engine will lbe completed and simultaneously thevstartingdw relay will cause operation of the starting motor,

thereby starting the engine. When the throttle valve is closed to such a position as to indicatev that the vengine should be stopped, the mercury switch |04 will be tilted to open position, this -65 deenergizing the ignition and the starting nie'chanism so that the engine stops. It will be lnoted that mercury switch |04 iso: the bent type) This type of switch is desirable here as it has va wide angle of ,operation and thus will prevent any 76 possibility of short-cycling of the apparatus.

While for illustrative purposes I have shown the engine controlling switch as being oLthe mercury Itype, it will be understood that any suitable frm` s o! switch may be employed.

- any other type of cooler. |16 is connected a pipe which in turn is operated valve H3. This valve H3 is shown as' being of the type which opens when deenergized and which closes when energized. This valve is ,controlled by eans of a controller ||4 which is responsive to the pressure Within the intake manifold 21 and comprises a bellows for actuating a mercury switch ||5. The controller |I4 is so arranged that when atmospheric pressure exists within the intake manifold 21, the mercury switch ||5 will be tilted to closed position, this resulting in opening of the valve I3. It will be Iapparent that when the engine is outof operation 4the intake manifold pressure will be substantially atmospheric, and -this will result in the valve H3 being held open. Thus, while the engine is being started, the compressor 20 in stead of compressing the refrigerant will merely force refrigerant from the discharge line into the suction line. 'Ihe compressor will, therefore, be unloaded during the starting operation of the engine. After the engine starts, however, a vacuum will be developed within the intake manifold 21, this causing contraction of the bellows to tilt the mercury switch ||5 to closed position as shown, whereby the valve |I3 is caused to close thus preventing further passage of refrigerant through the by-pass ||2. By this arrangement, therefore, the compressor is unloaded during the starting period of the engine and the load is automatically thrown on the compressor after the engine is in operation.

My invention also includes a novel arrangement for recovering the waste heat of the internal c mbustion engine and for recovering the heat given off by the condenser, this heat being made available for providing a source of heat supply which may be used for heating domestic water or for reheat. This heat recovery system will now be described in detail. Reference character ||0 indicates a source of cooled water, or other heat. exchange fluid which may take the form of an evaporative cooler, .a spray pond, or To the outlet of cooler connected to a pipe ||8 leading to theinl'et of the water circulating pump 3l. The discharge of pump 3l is connected by a pipe IIB to the cooling water inlet of the condenser 2|. The cooling water outletof the condenser 2| is connected by means of a pipe |20 to the inlet of the water jacket of the engine 2B. The water jacket outlet of engine 26is connected to a pipe |2| which lleads to the coil |22 of an exhaust gas heat exchanger |23, this heat exchanger being connected to the exhaust manifold 30 by means of an exhaust pipe |24. The outlet of the. heating coil |22 is connected to a pipey|25, this pipe leading to the inlet ofJa lthree-way valve |26. This three-way valve |26. may be of any desired type and is herein shown for illustrative-purposes as being of the balanced piston type including afpair of `pistons Iorselective `covering orzuncovering a\pairof outlet ports. One outlet portpf the Ythree-way valve is connected by a diipefllto the heating coil |28 may be located f f\ -iina storage tank as |23.' The outlet of coil |28 the cooler I I6.

From the arrangement described thus far, it

will be seen that cooling fluid is first passed through the condenser for condensing the refrigerant, and that this fluid is heated by the heat removed from the refrigerant during the condensing action. The heated fluid after leaving the condenser is further heated by passage through .the jacket of the internal combustion engine and is still further heated by passage in heat exchange relationship with the exhaust gases from the engine. The fluid leaving the exhaust gas heat exchanger |23 is therefore highly heated, and this fluid is passed either through the heating coil |28 of the storage tank or heat accumulator |29, or through the -by-pass |32 around such coil, or partly through the heating coil and through the by-pass, depending upon the position of the three-way valve.v The position of the three-way valve is controlled in accordance with the temperature Within the tank |29 by means of a temperature controller |35 anda proportioning motor |36 which is arranged to actuate said valve. The controller |35 is similar to the temperature controller 42 which has previously been described and therefore is not described in detail. It will be noted, however, that the control bulb of this controller is located within the storage tank |29 so that the position having the effect of reducing the flow of heated fluid through the heating coil |28 and increasing the flow of heated water through the by-pass. Thus, as the tank temperature increases, the supply of heated fluid to the heating coil is reduced. Upon a fall in temperature of the tank, it will be apparent that the opposite action Will take place, namely, the three-way valve |26 will be `positioned so as to increase the supply of heating fluid to the coil |28. In this manner the supply of heating fluid to the coil I 28 is con trolled for maintaining the tank temperatureconstant, thereby preventing overeating of the ywater or other fluid in said tank.

As mentioned before, the fluid which passes through the coil |28` and the by-pass |32 is reunited in the pipe |36 and flows to the inlet of the three-way valve |3|. This three-way valve has one outlet which is connected by a pipe |38 to the inlet of the lcooler II6, the other outlet of said three-way valve being connected to the pipe ||8 which in effect forms a by-pass around The three-way valve |3| therefore acts to control the quantity of fluid which is passed through the cooler II6. Thisk threeway valve is controlled in a manner to prevent the temperature of the cooling fluid being supplied to the condenser from exceeding a predetermined value, this being achieved by the use of a proportioning motor |40 and `a temperature controller I4I. The temperature controller I4I is similar to the controllers 42 and |35 and the control bulb of the controller I4I is located so ture to increase.

as to be responsive to the temperature of the cooling fluid passing to the condenser. For convenience in disclosure, I have shown this control bulb as located at the inlet of the pump. It will be understood, however, that if desired this bulb may be placed at the pump outlet. The controller I4| is connected to the proportio'ning motor |40 in such a manner that upon an increase in temperature of the cooling fluid flowing to the condenser, the motor |4| will position the three-way Valve for increasing the flow of cooling fluid through the cooler |I6 and decreasing the flow through the by-pass, thereby counteracting the tendency of the tempera- Conversely, if the temperature of the cooling fluid for the condenser falls, the three-way valve will be positioned to decrease the portion of the fluidy flowing through the cooler and to increase the portion flowing throughthe by-pass. By this arrangement, it will be apparent that no more cooling fluid is passed through the cooler II6 than is necessary to prevent the temperature of such cooling uid from exceeding a predetermined value, such as 100 F. 'I'he cost of heat dissipation is thereby held at a minimum yand at the same time all of the heat which can be utilized for reheating or for domestic water or other uses is retained by the system.

It will be understood that the heated liquid in tank- |29 may be used for any desired purpose,

including the provision of heating fluid for the reheater I9. For providing' the reheater I9 with heating fluid,-a pipe |45 is connected to the upper end of the tank |29, this pipe leading to the inlet of reheater I9. The outlet of reheater I9 is connected by means of pipe |46 to the intake of a circulating pump |41, this pump being driven by an electric motor |48 and discharging into the inlet of a three-way valve |49. One outlet of the three-Way valve is connected to the bottom of the tank |29 by means of a pipe |50 and the other outlet of said valve is connected by a pipe I5| to the pipe |45, this pipe I 5| thereby forming a by-pass for the flow of water `around the tank |29. The three-way valve |49 is positioned by means of a proportioning motor |52, this proportioning motor being also arranged to actuate a switch |53 which is in the circuit of the pump motor |49, said switch beingarranged to stop the pump whenever the three-way valve is positioned so that the flow of water through pipe |50 is shut off. It should be apparent that adjustment of the three-way valve |49 will change the proportions of the hot liquid from the tank |29 and the reci'rculated liquid passing through the by-pass.

which are passed to the reheater I9, and will therefore vary the temperature of the heating medium supplied to said reheater.

The proportioning motor |52 and therefore the temperature of the heating medium supplied to the reheater is controlled by the humidity controller I8 which also controls the face and by-pass dampers I2 and now to the humidity controller I8, this controller comprises a humidity responsive device comprisl ing aplurality of strands |55 of hair or other moisture responsive material, these strands being secured at their upper and lower ends by clamping members |56 and |51, the lower clamping member |51 being secured to a suitable fixed element. The upper clamping member |56 is connected to the actuating armIB'of a bell- I3. .Referring y rotated in a clockwise direction.

crank lever having a control arm |59 cooperating with a'control resistance |60 to form a control potentiometer. A tension spring |6| is attached to the end of'control arm |58 for urging said arm upwardlyto stress the strands |55. The control arm |55 is also arranged to actuate a second control arm |62 by any suitable means, this control arm I 62 cooperating with la control resistance |63 foi` forming a second control potentiometer. The control potentiometer formed of arm |59 and resistance |60 is connected to the damper actuating` motor |5,

and the control potentiometer formed of arm |62 and resistance I 63 is connected to the proportioning motor |52 for the reheat control valve. Upon an increase in humidity, the strands |55 will increase in length, this permitting the spring |6| to cause rotation ofthe arms 59 and 62 in a clockwise direction, while upon a decrease in humidity the strands |55 will-decrease in length, thus causing `rotation of the arms |59 and |62 in the opposite direction.

It will be noted that the resistances |60 and |63 each occupy but one-half of the range of movement of their respective control arms, contact segments being provided for said lcontrol arms when they are positioned so as to disengage their respective'resistances. The purpose of vthis arrangement is to provide al'sequential control for the dampers and the reheat control valve. With the control arms in the positions shown,it will be noted that the control arm |59 is engaging the midportion ofI the'resistance |60 and for this position of said control arm, the proportioning motor lr6 has assumed a position in which the faceand by-pass dampers |2 and |3 `are each half open. At this time, the control arm |62 is entirely oi the control resistance 163 and is engaging the contact segment which is connected to the left-hand end thereof. For this position of the control arm |62, the proportioning motor |52 has assumed anextreme position in which all flow 4of heated iluid from the storage tank |29 is stopped and in which also 'the mercury switch |53\is tilted tov open position for placing the pump |41 out of.

operation. -If the space relative humidity increases, the control arms |59 and |62 will be The movement of control arm |59 pn the resistance |60 Iwill cause the proportioning motor i6 to correspondingly close the face dampers |2 and Aopen the by-pass dampers I3. The corresponding movement of the control arm |62 will have no eiect upon the proportioning motor |52, as said control arm will still be engaging the contact" segment. When the relative humidity increases to such an extent that both arms |59 and |62 are upright, it will be `apparent that the face dampers I2 will be completely closed and the by-pass danpers |3 will be wide -open and that also the three-way valve motor |52 will be in the position shown, in which the pump |41 is out of operation; If nowshould the relative humidity increase further, the face dampers will remain closedI and the by-pass dampers open, due to the arm l|59 then engaging the conthis causing the positioning of the three-way valve |49 to supply heating iluid to the reheater,-

the mercury Switch |53 being tilted to cause increase in relative humidity, the three-Way valve will be positioned to increasey the portion of heated fluid supplied to the reheater I9 thereby increasing the heating ellect of said reheater. From the foregoing description, it should be apparent that when the relativehumidity is low the reheater will be out of operation and the by-passdampers closed and the face dampers open. As the relative humidity increases, the-dampers will gradually be 'positioned so as to cause closing of the face dampers and opening of the by-pass dampers, the reheater being still out of operation. When, however, the by-pass dampers are wide openand the relative humidity continues to inorease,`the

reheater will be placed into operation and the heating effect thereof will be increased upon further increase in relative humidity.

Gperaton WithA the parts fin the position shown, the space temperature is at an intermediate value as indicated by the control arm 16 of thes'pace temperature controller engaging the center of its cooperating resistance, and for this valve of space temperaturev the suction pressure controller is maintaining an intermediate value'of suction pressure as indicated by the control arm 61 of the suction pressure controller engaging the center' of its cooperating resistance. For

this position the throttle valve 29 is at half open position and the mercury switch |04 is tilted to' closed position. The engine 26 isth'erefore in operation for maintaining the" desired temperature of the cooling coil |0. Also the space relative humidity is slightly excessive as inditemperature,

cated by the control arm |59engaging the midportion of the control resistance |60, andfor this value of humidity the face and by-pass dampers are/positioned so that part of the air flows across the cooling coil and an equal part is by-passed therearound.

If now should the space temperature increase,

due, for instance, to increasing outdoor temperature, two actions for increasing the speed of the compressor will occur. Due to the higher temperature of the air flowing across the cooling cil |0, an increased amount of refrigerant will be evaporated, vthis causing a -rise in suction pressure. In response to this rise in suction pressure, the pressure ycontroller 4| will act on the throttle valve motor 440 for openingxsaid throttle valve ,somewhat to'cause an increase in engine speed. Also, `the return air temperature controller will act inresponse to the increase in' temperature to demand alower cooling coil this additionally affecting the throttle valve motor 40 for increasing the engine speed'. Due to this lowering in coolingcoil teincrease in the cooling load, the temperature conf y tact segment connected to the right end of resistance |60. Now, however, the control arm l| 62 will be riding the control resistance 63, 79'

perature caused by the return air temperature controller 42, an increased amount of heat will be absorbed by the cooling coil I0, this acting to stopthe rise in temperature withinthe conditioned space.- If fthe temperature should-decrease within the'conditioned space due to detroller 42 will act to adjust the suction pressure controller 4| inx a manner to maintain a higher K coil temperature.` Due to this adjustment, and

also due to the fact that less refrigerant will be evaporated `by the ycooler air, which tends to] cause a reduction in suction pressure., the suction pressure controller l4| will act to cause closing of the throttle valve 29, which in turn results in slowingI down of ,the engine. 'Due to the higher coil temperature now maintained, the cooling effect', of the cooling coil |0 will be reduced, thereby preventing further fall in temperature of the air within the conditioned space.

It will be apparent that as the cooling load decreases, the control system described will cause progressive closing of the valve 29, and that when the throttle valve is closed to such an extent that mercury switch |04 is tilted to open position, the engine 26 will stop. Also, assuming the engine to be stopped, as the demand for conditioning increases, the throttle valve 29 will be opened and when it is opened sufliciently to cause closing of mercury switch |04, the engine will be automatically started, the compressor unloading valve ||3Y being opened during the starting period for the engine and being automatically. closed after the engine has started. l

Assuming again that the system is in operation, if the relative humidity should increase, the humidity controller I8 will cause closing movement of the face dampers I2 and opening movement of the by-pass dampers I3. This will result in decreasing the rate of air ow across the cooling coil |0, which in turn will result in decreasing the cooling eiect of said coil. This decrease in the cooling action of the coil will eventually result in a rising space temperature, and in response to this rising temperature, the temperature /controller 42 will adjust the controller 4| for maintaining a lower suction pressure. This will result in lowering the temperaternal combustion engine is utilized, the temperature Within the tank |29 will fall to such an extent that the temperature controller |45 causes all of the heated uid to be supplied to the heating coil |28. However, as the demand for heated fluid decreases, the temperature in tank |29l will increase, this resulting in the temperature controller |35 causing movement of the three-way valve for decreasing the flow of fluid through the coil |28. This will result in the temperature of the mixture of water from the by-pass and the coil |28 increasing, which in turn will cause the temperature of the mixture of water owing to the condenser to increase. In response to this increase in cooling Water temperature, the temperature controller |4| will position the valve |3| in a manner to cause flow of a suiicient part of the water through the cooler ||6 as to prevent the temperature of the cooling water supplied to the condenser from becomingYV excessive.

Referring now to Figure 2, this figure shows exactly the same air conditioning apparatus as lsh'own in Figure 1, and hence this apparatus is ture of the cooling coil |'0 thereby increasing the dehumidifying effect of said coil to counteract the increase in humidity. If the relative humidity should continue to increase, the face dampers I2 will be further closed and the bypass dampers I3 further opened, thus decreasing the cooling effect of the coil |0 even further for causing a higher space tmperature, which in turn will result in the space temperature controller 42 demanding an even lower coil temperature lfor counteracting such increase in relative humidity. After the by-pass dampers I3 are wide open and the face dampers |2 are moved to their minimum position, if the relative humidity should continue to increase, the reheater |9 will be brought into operation for actually heating the air supplied to the space for causing such a space temperature rise as will result in the space temperature controller demanding lower coil temperatures. Upon falling humidity, it will be apparent that the opposite action will take place, namely, the reheater I9 will be placed out of operation and then the face dampers will be gradually opened and the by-pass dampers gradually closed, this resulting in the reverse eiect upon the temperature controller 42 for raising the coil temperature to decrease the dehumidifying eect thereof. By this sequential damper and reheat control, it will be apparent that addition of heat to the air is avoided at all times except when absolutely necessary for lowering the relative humidity to the desired value.

It should be noted that the -control by the threeway valves |26 and |3| will automatically prevent the temperature` of the liquid in the tank |29 from becoming excessive and will also act to dissipate just enough heat in the cooler ||6 as to prevent the temperature of the cooling water supplied to the condenser from becoming too high. Thus if the demand for domestic lhot water or other heated uid is such that all of the heat recovered from the Lcondenser and the innot described here in detail. This figure shows several modifications which may be made in the control apparatus, which Will now be described.

In Figure 1, it will be noted that the solenoid unloading valve ||3 is controlled by meanslof a controller responsive to the manifold pressure of the engine. In Figure 2, I have shown a solenoid valve ||3a which corresponds to the valve ||3 of Figure 1. 'I'his valve ||3a, however, is of the type which opens when energized and Ywhich closes when deenergized. This valve, instead of being controlled by an engine manifold pressure controller as in Figure 1, is energized simultaneously with the starting motor 32 of the internal combustion engine 26. For this purpose the solenoid valve |3a is connected by a wire 200 to the wire 20| which leads fromthe relay |||-to the starting motor 32. By this arrangement, when the starting motor 32 is energized by the starting 'relay Vthe valve |3a will be energized thereby causing it to open; Therefore, when the internal combustion engine 26 is being started, the valve ||3a is opened, which permits bypassing of refrigerant fromthe discharge of the compressor to the suction side, thereby unloading the compressor to permit starting of the engine. When the engine starts, the relay will deenergize the starting motor, and will 'simultaneously deenergize the valve ||3a,v this causing said valve to clos'e for placing the refrigeration system in operation.

As in the case of Figure 1, the throttle valve 29 of the engine is actuated by a proportioning motor 40 under., the control of a return duct temperature controller 42. In this figure, however, the internal wiring of the motor 40 has not been illustrated, and for convenience, the mercury switch |04 is illustrated as being actuated by the actuating arm` 44 of the motor 40.

If desired, the control system may be arranged to place the entire air conditioning system out of operation Whenever the fan motor 5 is deenergized. For this purpose, I have shown a relay 202. This relay consists of a relay coil 203 which actuates through a suitable armature (not shown) a switch arm 204 which cooperates with contact 205. The switch arm 204 and contact 205 are interposed in the wire |09 which leads from the mercury switch |04 to the starting relay The relay coil 203 is connected by wires 8b and 9b to the line Wires 8a and 9a to which are connected the wires 8 and 9 leading to the fan motor 5. n When the. lineswitch to -line wires 8a and 9a is closed, thefan motor 5 will be energized for causing a flow of air through thev conditioning chamber. Also at this time, the relay coil 203 will be energized which causes engagement of switch arm 204 with contact 205. This completes the circuit from mercury switch |04 to the starting relay III and thereby places the mercury switch |04 in control of the engine for starting and stopping the same. When the line, switch for the fan is opened, however, the relay-coil 203 will be deenergized, which causes switch arm 204 to disengage contact 205 thereby breaking the circuit from mercury switch |04 to the starting relay. This will prevent the starting relay ||I from starting the engine and will also deenergize the ignition coil IIO. This arrangement therefore preventsoperation of the engine 26 whenever the fan is not operating.

vMy invention also contemplates the provision .of an arrangement for preventing the reheater1 I9 from overheating the space. It will be apparent that when the reheater is controlled by means of a humidity controller, if the humidity becomes excessive, the humidity controller may cause the l reheater to deliver heat to the space in suchan amount as to actually heat up the space. In order to prevent this action, I have provided a reheat limit controller generally designated at The bellows 2|5 is connected by a capillary tube 2| 8 to a control bulb 2|9 located within; the discharge duct 6. It will be understood thateach. bulb contains a suitable volatile fluid for causin varying pressures to be yexerted upon the respective bellows upon changes in temperature at the control bulbs. The control arm 2I| is biased by means of a spring 220, this spring tending to,

cause said control arm to move tothe left across the controlresistance 2I3. By this arrangement, it will be apparent that when the return and discharge temperatures at the. control bulbs are equal, .the pressures within bellows l2I4 and 2|5 will be equal, thereby causing the spring 220-to urge control arm 2|| towards the left-end of rehowever, the limit controller 2I0 will act to position the proportioning motor I 52 independently of the humidity controller I8 to cause the heating effect of reheater I9 to be reduced. This arrangement will now be described. y

The proportioning motor |52 is of the same type as the proportioning motor which has beenvdescribed in detail in Figure l, and includes a balancing relay of the type diagrammatically illustrated at in Figure 1. This relay 50,

it will be noted, consists of relay coils 54 and 55 which are connected together, and a wire leading from their junction point. This wire in the art is termed the red wire. Also. the other ends of the relay coils are connected to control wires which are termed the white and blue wires. From the description of Figure 1, it should be apparent that the position assumed by the proportioning motor will be dependent upon the resistance connected between the red`and white wires and between the red and blue wires.v Thus,

when the resistance between the red and white wires is equal to the resistance between the red and blue Wires, the motor will assume mid-position. When, however,- the resistance between the red and white wires is increased, Aand the resistance between the red and blue wires is decreased,

themotorwill move in one direction to anew position. Similarly, when the resistance between the red and blue wires is increased and the resistance between the `red and white wires decreased, the motor will move in the opposite direction to a new position.

As shown, the red terminal of the motor |52 is connected by a wire 22| to the control arm 2| I of the limit controller 2I0. The white terminal of the motor |52 is connected by wires 222, 223

Y and 224 to the left-hand ends of the control resistances 2|3 and |63. The blue terminal of the motorv is connected by a wire 225 to the righthand end of control resistance I 63, while the control arm |62 is connected'` by a wire 226 to the,

right-hand end of control resistance 2I3.

Under normal operation, the predetermined difference in temperature between the return air and discharge air will exist, this causing theV 2I| to engage the extreme rightcontrol resistance 2I3. This causes,

control arm hand end of the control arm |62 of the humidity controller sistance 2I3. When the temperature of the discharge airis lower than the'temperature of the ireturn air, however, agreater pressure will beA exerted within `bellows 2I4v than 'within the bellowsj2|5,this urging 'the control arm 2I| against the action of the spring 220- towards the righthand end of control resistance 2I3. It will be i apparent that when the discharge airI temperacontrol circuitA of the reheat proportioning motor |52 in a manner to place the humidity controller I8 in vfull control of said proportioning motor determined amount lower than'the return air temperature. When this diierential in temperaf ture decreases below the predetermined value,

to, be connected to the red terminal ofthe motor |52 as follows: wire 22|, control arm 2| I, righthand end of control resistance 2I3, and wire 226 to control arm |62. At this time, it will vbe noted, the control resistance 2I3 is connected between the red and White terminals of th motor |52 byowires 22|, 223. and 222. To balance out the effect of this resistance on the motor relay, a resistance 221 is'connected betweenwires 226 and 225. This resistance is equal Yifi/value to the resistance 2|3 and is connected between the red and blue terminals of the motor as follows: red terminal of motor, wire 22|, control arm 2|I, wire 226, resistance 221 and wire 225 to the blue terminal of the motor. By this arrangement, it 'will be apparent. that when the predetermined difference in temperature exists between the return air ndthe discharge air, the controller 2 I0 will place thelhumidity controller in full controlof the proportioning motor |52 for controlling the supply of heating iluid to the y reheater` I9.. ,whenever the discharge air temperatureis a pre, y

f the, reheater If` now.shou'ld too much heat be suppliedto l by the humidityvcontrouer |a the discharge air temperature 'will rise to such a value that the difference'in temperature between the return and discharge air falls below the predetermined value. This will cause the control arm 2H to be shifted towards the left across control resistance 2|3, this decreasing the portion of said resistance which is connected between the red and white terminals of the motor and increasing the portion ofr said resistance which is connected between the red and blue terminals of the motor. This, in a manner which should now be apparent, will cause movement of the motor |52 in a direction for reducing the supply of heated iluid to the reheater. rI'he limit controller 210 therefore acts to prevent the reheater I9 from delivering too much heat to the air being conditioned, thereby preventing actual heating of the conditioned space and uneconomical operation of the system. ,l

While I have shown a reheat limit controller which is responsive to the difference between the temperatures of the return and discharged air, it will be apparent that if desired, the limit controller may be made responsive to space temperature, and arranged to prevent operation of the reheater when the space temperaturevis excessive.

From the foregoing description, it should be apparent that I have provided an air conditioning system which is especiallyadapted for internal combustion engine drive, such system acting to automatically maintain proper temperature and humidity conditions within the conditioned space, and further providing for recovery of the heat dissipated by the system and for automatically dissipating only such portion of such recovered heat as is not necessaryfory other uses.

While my invention relates to air conditioning systems utilizing internal combustion engines, it will be apparent that certain features are of broader application, having utility apart from air conditioning or apart from internal combustion engine control. It will also be apparent that many changes which are within the scope ofVx invention will be apparent to those skilled in my the art. I, therefore, desire to be limited only by the scope of the appended claims and the prior art.

I claim as my invention:

1. In a system of the class described, in combination, a cooling device, means for supplying a cooling medium to said cooling device includinga compressor, means for graduatihgly varying the output of said compressor, control means influenced by the temperature of said cooling device for; controlling said varying means to vary compressor output for maintaining the temperature of the cooling device substantially constant, means responsive to a cooling load affecting condition for adjusting said control means for determining the cooling action maintained thereby, and means ractuated with said compressor output varying means and arranged to place said compressor out of operation when said varying means reduces the operation of said compressor to a predetermined minimum value.

2. In a refrigeration system, iny combination, an evaporator, means for supplying refrigerant to said evaporator, a` compressor for reducing the pressure in said evaporator, a controller for varying the output of said compressor, a device responsive to the pressure in said evaporator for positioning said controller to cause a constant pressure to be maintained within said evaporator, f

means responsive to a condition aiecting the re- -a controller for varying the output of said internal combustion engine, control means iniiuenced by the temperature of said cooling device for controlling said controller to vary the engine output in a manner to maintain the cooling device at constant temperature, and means responsive to a cooling load aiecting condition of lthe air in the space being conditioned for adjusting said control means to thereby cause the cooling eiect of the cooling device to be varied in accordance with said condition.

. 4. In an air conditioning system, n combination, a cooling device, means for passing air in heat exchange'relationship with said cooling device and to a space to be conditioned, means for supplying a cooling medium to said cooling device including a compressor, a controller for varying the output of said compressor; control means influenced by the temperature of said cooling device for causing actuation of said controller to maintain the cooling device at constant temperature,` means responsive to a cooling load affecting condition of the air in the space being conditioned for adjusting said control means to thereby cause the cooling effect of the cooling device to be varied in accordance with said condition, and means actuated by said control means with said controller for terminating operation of said compressor when said controller reduces the compressor output to a predetermined value.

5. In a system `of the class described, a refrigeration system having a condenser and a compressor, an internal combustion engine for driving said compressor, heat exchange means for recovering waste heat from said internal combustion engine, heat utilizing means, means for passing heat exchange iluid through said condenser, said waste heat recovering means. and said heat utilizing means, means for passing heat exchange iluid from said utilizing means to said condenser including a heat dissipating means, by-pass means for said uid around said heat dissipating means, and automatically controlled valve means for varying the proportions of said iiuid passed through said heat dissipating means and said by-Pass.

6. In a system of the class described, a refrigeration system having a condenser and a compressor, an internal combustion engine for driving said compressor, heat exchange means for recovering waste heat from said internal combustion engine, heat utilizing means, means for passing heat exchange fluid first through said condenser, then through said waste heat recovering means and then through said heat utilizing means, means for passing heatv exchange fluid from said utilizing means to` said condenser including a heat dissipating means, by-pass means for said uid around said heat dissipating means, valve means for varying .the proportions of the iluid passed through said heat dissipating means and said by-pass means, and means responsive tothe temperature of the heat exchange fluid entering the condenser for controlling said valve means.

7. In a system of the classdescribed, a refrigeration system having a condenser and a compressor, an internal combustion engine for driving said compressor, heat exchange means for recovering waste heat from said internal combustion engine, heat utilizing means, means for passing heat exchange iluid through said condenser to said heat utilizing means, by-pass' means around said heat utilizing means, valve means associated with said by-pass means for varying the` proportions of the heating fluid passedv through said heat utilizing means and said by-pass means, means'for passing heat exchange fluid from said utilizing means to said condenser includinga heat dissipating means, by-pass means for said fluid around said heat dissipating means, and automatically controlled valve means for varying the proportions of said fluidpassed through said heat dissipating means and said last mentioned by-pass means for controlling the heat content of the fluid being supplied to said condenser.

'8. In a system of the class described, arefrigerationv system having a condenser and a compressor, an internal combustion engine for driving said compressor, heat exchange means for recovering Waste heat from said internal combustion engine, heat utilizing means, means for passing heat exchange fluid through said heat exchange means to said heat utilizing means, means for passing heat exchange fluid from said utilizing means to said condenser including a heat dissipating means, by-pass means for said fluid around said heat dissipatingmeans, and

' automatically controlled valve means for varying the proportions of said fluid passed through said heat dissipating means and said last mentioned by-pass means for controlling the heat content of the fluid being supplied to said condenser.

9. In a system ofthe class described, a refrigeration system having a condenser and a compresser, an internal combustion engine for driving said compressor, `heat exchange means for recovering Waste heat from said internal combustion engine, heat utilizing means, means for passing heat exchange fluid through said heat exchange means to said heat utilizing means, means for passing heat exchange uid from said utilizing means to said condenser, valve means for adding cool heat exchange fluid to saidv heat exchangeV fluid passing to said condenser, and

. means for controlling said valve means in a manner' to prevent the temperature of the heat exchange iluid being delivered to the condenser from exceeding a predetermined value.

10. In an air conditioning system, in combination, a conditioning chamber through which air delivered to a space is adapted to be passed for a conditioning ,action, a cooling device in said conditioning chamber, means including a device responsive to the temperature of the space in control of said` cooling device, by-pass means around said cooling device, damper meansI for controlling the proportions of the air passed throughsaid cooling 'device and said by-pa'ss.l a reheating device for reheating the air, and

moisture responsive means for` sequentially controlling said damper means and said reheating device.

11. In an air conditioning system, in combination, a conditioning chamber, means .for

causing flow through said chamber of air to be conditioned, a cooling and dehumidifying device in said chamber, a. reheating device in said chamber, temperature responsive means for controlling saidcooling and dehumidifying device, humidity responsive means for controlling said r reheating device to reheat the air cooled by said 12. In a system of the class described, a refrigeration system including an evaporator and a compressor, an internal combustion engine for driving said compressor, a speed controller for varyingr the speed of said engine, control means influenced by the temperature of the evaporator for graduatingly adjusting said speed controller in a manner to maintain the evaporator temperature substantially" constant, means responsive to a condition affecting the load on the system for adjusting said control means-to thereby vary the evaporator temperature maintained in accordance with variations in said condition, and l means actuated by said control means with said speed controller for starting and stopping said engine, said last mentioned means being arranged to cause starting of the engine when the speed controller is adjusted for a predetermined minimum speed and for causing stopping vof the engine when the speed controller is adjusted to cause engine operation below said predetermined minimum.

13. In a system of the class described, a refrigeration system including an evaporator and fa compressor, an internal combustion engine for driving said compressor, a speed controller for varying the speed of 'said engine, control means influenced by the temperature of the evaporator for graduatingly adjusting said speed controller in a manner` to maintain the evaporator temperature substantially constant, means responsive to a condition affecting th`e load on the system for adjusting said control means to thereby vary the evaporator temperature maintained in accordance with variations in said condition, and means actuated by said control means with said speed controller for starting said engine when said speed controller` is adjusted to obtain an engine speed above a predetermined value.

14. In a system of the class described, a refrigeration system includingl an evaporator, and a compressor, an internal combustionl engine for driving said compressor, a speed controller for varying the speed of said engine, control means influenced by the temperature of the evaporator for graduatingly adjusting said speed controller in a manner to maintain the evaporator temperature substantially constant, means responsive to acondition affecting the load on the system for adjusting said control means to thereby vary the` evaporator temperature maintained in accordance with variations in said condition, and means actuated by said control means with said speed controller for stopping said engine when said speed controller is adjusted to reduce the., engine speed below a predetermined value. 15. In a system of the class described, a cooling device, means for passing. air in heat exchange relationship with said cooling'gdevice and to a space to be conditioned, means for supplying cooling medium to said cooling device including a compressor, said compressor having .an inlet and an outlet, a by-pass connecting said inlet and outlet, an unloader valve in said by-pass for unloading said compressor, an internal combustion engine for drivingv said compressor, said engine having a speed controller and a starting motor, control means influenced by the cooling effect of the cooling device for graduatingly adjusting said speed controller, means responsive to a condition affecting the load on the system for adjusting said control means to thereby vary the cooling eiect of the system in accordance with variations in said condition, means actuated by said control means with said speed controller for energizing said starting motor when the speed controlleris adjusted to demand an engine output above a predetermined minimum, and means for causing said unloader valve to be open when said starting motor is in operation.

16. In a system of the class described, a cooling device, means for passing air in heat exchange relationship with said cooling deviceand to a space to be conditioned, means for supplying cooling medium to said cooling device including a compressor, said compressor having an inlet and an outlet, a by-pass connecting said inlet and outlet,`an unloader valve in said by-pass for unloading said compressor, an internal combustion engine for driving said compressor, said engine having'a speed controller and a starting motor, control means responsiveto the demand forrefrigeration in said space for graduatingly adjusting the speed controller in accordance with such demand, means actuated by said control means with said speed controller for energizing said starting motor when the speed controller is adjusted to demand an engine output above a predetermined minimum, and means for causing said unloader valve to be open when said starting motor is in operation while closing said unloader valve after the engine is in operation.

1'7. In arsystem of the class described, a. cooling device, means for passing air in heat exchange relationship with said cooling device and to aspace to be conditioned, means for supplying cooling medium to said cooling device including a compressor, said compressor having an inlet and an outlet, a by-pass connecting said inlet and outlet, an unloader valve in said by-pass for unloading said compressor, an internal combustion engine for driving said compressor, said engine having a speed controller and a starting motor, control means influenced by the cooling effect of the cooling device for graduatingly adjusting said speed controller, means responsive to a condition aecting the load on the system for adjusting said control means to thereby vary the cooling eilect of thefsystem in accordance with variations in said condition, means for energizing said starting motor upon demand for refrigeration in said space, and means for causing said unloader valve to be open when said starting motor is in operation while closing said unloader valve after the engine is in operation.

18. In a system of the clas's described, a cooling device, means for passing air in heat exchange relationship with said cooling device and to a space to be conditioned, means for supplying cooling medium to said cooling device including a compressor, said compressor' having an inlet and an outlet, a by-pass connecting said inlet and outlet, an unloader valve in said by-pass for unloading 'said compressor, electromagnetic means adapted when energized to open said unloader valve, an internal combustion engine for driving said compressor, said engine having a speed controller and a starting motor, control means responsive to the demand for refrigeration in said space for graduatingly adjusting said speed controller in accordance with such demand, switching means actuated by said control means with said speed controller for energizing said starting motor and said electromagnetic means when the speed controller is adjusted to demand an engine output above a predetermined minimum, and means for deenergizing said starting motor and said electromagnetic means after said engine is in operation.

19. In a system of the class described, acooling device, means for passing air in heat exchange relationship with said cooling device and to a space to be conditioned, means for supplying cooling medium to said cooling device including a compressor, said compressor having an inlet and an outlet, a by-pass connecting said inlet and outlet, an unloader valve in said by-pass for unloading said compressor, electromagnetic means adapted when energized to open said unloader valve, an internal combustion engine for driving said compressor, said engine having a starting motor, switching means responsive to a demand for refrigeration in said space for energizing said electromagnetic means and said starting motor, and means actuated in response to operation of the engine for deenergizing said starting motor and said electromagnetic means after said engine is in operation.

20. In a system of the class described, in combination, a conditioning chamber through which air is passed to a conditioned space, a cooling device in said chamber, a by-pass for air around said cooling device, damper means for controlling the proportions of the air owing through said cooling device and by-pass, means for supplying cooling medium to said cooling device including a compressor, an internal combustion engine for driving said compressor, said engine having a starting motor and a speed controller, control means influenced by the temperature of the cooling device for adjusting said speed controller for maintaining the cooling device at constant temperature, means responsive to the temperature of the space for adjusting said control means in a manner to decrease the temperature of said cooling device upon rise in space temperature, switching means actuated by said control means for energizing said starting motor when said controller is adjusted to demand an engine output above a predetermined value, and means responsive to the humidity in said space for controlling said damper means.

21. In a system of the class described, combination, a conditioning chamber through which air is passed to a conditioned space, a cooling device in said chamber, a by-pass for air around said cooling device, damper means for controlling the proportions of the air flowing through said cooling device and by-pass, means for supplying cooling medium to said cooling device including a compressor, an internal combustion engine for driving said compressor, said engine having a starting motor and a speed controller, control means influenced by the temperature of the cooling device for adjusting said speed controller for maintaining the cooling device at constant temperature, means responsive to the temperature of the space for adjusting said control means in a manner to decrease the temperature of said cooll ing device upon rise in space temperature, switch- ,ving means actuated by said control means for energizing said starting motor when said controller is adjusted to demand an engine output vabove a predetermined value, a reheater for reheating air cooled by said cooling device, means for delivering waste heat from the engine to said reheater, and means responsive to .the humidity in said space for controlling said damper means and said reheater. t

22. In an air conditioning system, in vcombination, a conditioning chamber through which air l is passed to a conditioned space, a cooling device in said chamber, a by-pass for air around said `cooling device, damper means forcontrolling the proportions of the air passed through said cooling device and said by-pass, means responsive to the humidity of the air in said space for graduatingly controlling said damper means in a manner to decrease the flow of air through said cooling device upon increase in humidity, means inuenced by the temperature bf the 'cooling device for maintaining said cooling device at; constantl temperature, and means responsive to the temperature in said space for adjusting said last mentioned means in a manner to lower the temperature of the cooling device upon rise in space temperature.

23. In an air conditioning system, in combination, a conditioning chamber through which air is passed to a conditioned space, a cooling device in said chamber, aby-pass for air around said cooling device, damper means for controlling the proportions of the a-ir passed through said cooling device and said by-pass, means responsive to the humidity of the air in said space forgraduatingly controlling said damper means in a mannerrto decrease the ow of air through said cooling device upon increase in humidity, and means responsive to the temperature of the air in said space for graduatingly lowering the temperature of said cooling device upon rise in space temperature.

24.l In' an air conditioning system, in combination, a conditioning chamber through which air is passed to a conditioned space, a cooling device in said chamber, a by-pass for air around said cooling device, damper means for controlling the proportions oi the air passed through said cooling device and said by-pass, a reheater for heating the air cooled'by said cooling device, meansresponsive to the humidity of the air in said space for controlling said damper means and said reheater in a manner to decrease the flow of air through said cooling device to a minimum upon rise in humidity to a predetermined value and then to place said reheater in operation upon continued rise in humidity,'and means responsive tothe temperature of the air in said space for g-raduatingly lowering the temperature of said cooling device lupon rise in temperature.

25. In an air conditioning system, in combination, a conditioning chamber through which air is passed to a conditioned space, a cooling device in said chamber, a by-pass for air around said cooling device, damper means for controlling the proportions of the'air passed through said cooling device and said by-pass, a reheater for heating the air cooled by said cooling device, and means responsive to the humidity of the air in .said space for controlling said damper means and said reheater in a manner to decrease the flow of air through said cooling device to a minimum upon rise in humidity to a predetermined value and then `to place said reheater in operation upon continued rise in humidity.

26. The combination of a compressor, an internal combustion engine with an exhaust manifold, a cranking motor put in motion by a starter switch to start said engine, a by-pass from the low pressure to the high pressure side of the` 2'7.`The combination of a compressor, an in ternal combustion engine with an exhaust mani-` fold, a cranking motor to start said engine, a by-pass from the low pressure to the high pressure side of the compressor, an electrical valve controlling the by-pass, means to open said valve when cranking motor is energized and until it is de-energized, irrespective of the temperature of the engine.

28. In an air conditioning system, in combination, a conditioning chamber, means -for passing air to be conditioned through said chamber and to a space to be conditioned. a cooling and dehumidifying device in said chamber for cooling the air passing therethrough, meansresponsive to the temperature of the air in the space being conditioned for operating said device when the space temperature becomes too high whereby the air is cooled, a reheater in said chamber, means responsivev to the relative humidity of the air in the space for operating said reheater to raise the temperature of the air upon increase inhumidity, and other temperature responsive means in 

